In a packed hall in Westminster last Wednesday, a respected former Conservative cabinet minister railed against his own government. “Our current energy policy is a slave to flawed climate action,” declared Owen Paterson. “The [EU’s] 2050 target requires a reduction in greenhouse gas emissions by 80pc relative to 1990 levels,” he said. “Yet only the UK has made it legally binding through the Climate Change Act, a piece of legislation I and virtually every other MP voted for”.

Achieving this 2050 target is “entirely unrealistic”, argued Paterson, Environment Secretary until he was reshuffled out of government three months ago. “Yet despite this doomed policy, we provide subsidies for renewables of £3bn a year – and rising fast”. Much of this money goes towards funding wind-farms that further enrich “wealthy landowners and rich investors”, Paterson pointed out, while adding to the energy bills of “hard-pressed, low-income households”.

The MP for North Shropshire called on the Conservative government he was a member of until July to rein-in the “subsidy-drunk renewables industry and their green lobby friends” who back the 2050 targets. “This is the single most regressive policy we have seen in this country since the Sheriff of Nottingham,” he cried, to loud applause.

Onshore wind turbines, produce “nowhere near enough power to hit the 2050 target” and have already “devastated landscapes, blighted views and divided communities,” said Paterson.

“Offshore wind … with its gigantic costs and disappointing reliability … is proving a failure,” he continued. “The UK is the world leader in offshore wind technology, only because no other country has been stupid enough to plough so much public money into it”.

Other forms of renewable energy weren’t spared Paterson’s wrath, with hydroelectric power “maxed-out” and tidal and wave power “still too expensive and impractical”. Biomass fuel “generates more carbon dioxide per unit of energy even than coal”, and solar power is a “non-starter as a significant supplier … and will remain so as long as our skies are cloudy and our winter nights long”.

The Former Environment Secretary outlined a four-point plan to lower UK carbon emissions, as his audience listened attentively. His proposals included the rapid development of shale gas – “the UK is sitting on one of the richest shale deposits in the world” – to sophisticated energy demand-management, in particular the use of “smart-switches” to turn-off selected non-essential appliances during peak demand, so avoiding the cost of maintaining huge excess capacity.

Paterson wants to see the widespread use of small, localized nuclear reactors – “there’s been one in the centre of Derby for years” – together with the development of a network of gas-fired combined heat and power plants. “The generous EU estimate of the current efficiency in conventional power stations is 50pc,” he said. “The best of the CHP plans deliver 92pc efficiencies”.

Calling on the 300-strong Westminster crowd before him to “challenge current group-think” and “stand-up to the bullies in the environmental movement”, Paterson ended his speech by calling on his own government to “drop the 2050 target” and “repeal” the Climate Change Act.

“This would reinvigorate the freedom of science and business to explore new technologies,” he boomed, to sustained applause. “I’m absolutely confident that by doing this we can reduce our emissions and keep the lights on”.

As political speeches go, this was a corker. Sitting at the back of the hall, I saw before me a speaker at the top of his game and an audience transfixed. It was passionate, old-school oratory – the likes of which seems so rare in contemporary public life.

While most people there were supportive – Paterson’s speech was hosted by the Global Warming Policy Foundation, a pressure group broadly skeptical about climate change – the speech was criticized severely elsewhere. Many environmental campaigners described it as “mad”, “bonkers” and worse. And Paterson’s intervention certainly marked a sharp departure from the political consensus on climate change, a consensus he broadly supported until sacked by Prime Minister David Cameron.

In his Parliamentary office yesterday, his old ministerial red-box displayed prominently on the shelf above his desk, I asked Paterson why he’s changed his tune on climate change. What does he know now he didn’t know in government?

“I’m still open-minded it may one day turn dangerous and we should cut emissions, but as long as we don’t cause great suffering now for those on low incomes or unduly damage today’s environment,” he said.

“While I was concerned about wind-farms while a minister, I had little idea just how dire our broader energy policy is,” he said. “The Climate Change Act is completely disastrous – it’s been a shock for me in recent months to realized it won’t work in practice. You simply can’t build all the required non-carbon generation”.

Around 1,500 wind turbines produce 1GW of electricity, Paterson argues, out of an annual average of UK requirement of 36GW. “Where are we going to put them all?” he asks. “Across mid-Wales, where wind-farms are going up near my patch, there’s violent opposition, close to open insurrection”.

Describing the Climate Change Act as “extremely brutal”, he recalls that “given the zeitgeist of the time, when Ed Miliband was Environment Secretary in 2008, it was passed with support from all the main parties. But now, with other EU countries flouting the targets, and the Poles making all sorts of noises they won’t even try to comply, it should at least be suspended. Why should the UK be the only major country in the world doing this?”

While the green lobby has been “horribly abusive” since he gave his speech, Paterson reports he’s received a “wave of support” from elsewhere. “We’ve had sheds loads of e-mails, letters and phone-calls backing me,” he said. “Now I’ve stuck my neck out, and taken some flak, I’m hoping we’ll see a decent debate on this crucial issue”.

Reluctant to talk about his party leadership, and removal from office, Paterson warns that, when it comes to shale energy, “which the Prime Minister and Chancellor very much support,” the Tories are “losing the argument on the ground” to green campaigners. “They’re incredibly effective at leafleting houses, scare-mongering and stirring people up”.

He also cautions that, when it comes to discontent about wind-farms, Ukip has been “extremely good at latching onto the concerns of many small-c Conservatives – supporters we’ve lost and desperately need to get back”.

Posing as a “candid friend, the former Environment Secretary said he’ll be making a “series of thoroughly-researched statements, not least on Europe” over the coming months. Stressing his intention to “rally my party”, Paterson points to the “broad support” in the country for “fewer politicians, fewer bureaucrats, less regulation and less taxation”.

“Energy policy is clearly important as many of our natural supporters have had a tough time economically in recent years and object strongly to pay higher bills for renewable technology they know won’t work”, he says.

“I say to those at the top of my party that they need to wake up and not pursue policies that are repellent to the small-C conservatives that we need to get back from Ukip”.